function [s, c] = diffMapping2(stego, cover, dim)
    mapping = diffMapping(stego, cover, dim);
    [M, N] = size(stego);
    [L, N] = size(cover);
    stego = stego(:, mapping);
    cover = cover(:, mapping);
    paddingS = ones(M, 1) - sum(stego, 2);
    paddingC = ones(L, 1) - sum(cover, 2);
    s = [stego paddingS];
    c = [cover paddingC];
end